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aligning narrowband images

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  • CurtisC
    I may not even be asking the question properly, or I may not correctly understand what I ve been reading. I m getting into narrowband imaging (Ha, OIII,
    Message 1 of 11 , Jul 30, 2011
      I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16 leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
    • Ron Wodaski
      Let s start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in
      Message 2 of 11 , Jul 31, 2011
        Let's start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in that area of the sky where you are? (Ha does a good job blocking light pollution, but OIII and SII are susceptible to it.)

        Ron Wodaski



        On Jul 30, 2011, at 11:30 PM, CurtisC wrote:

        > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16
        > leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
        >
        >
        >
        > ------------------------------------
        >
        >
        >
        >
      • Bob Franke
        Hi Curtis, Yes, sometimes it s not good to look at Croman s work. The best way to do it is to align the images only once. First calibrate all of your Ha,
        Message 3 of 11 , Jul 31, 2011
          Hi Curtis,

          Yes, sometimes it's not good to look at Croman's work. <g>

          The best way to do it is to align the images only once. First calibrate all of your Ha, SII and OIII subs and save into folders called "calibrated". Then load all the calibrated subs, for each filter, into CCDStack at once, align them and save into another folder called "aligned". Now you can load all the aligned subs for one filter and create your Ha, SII and OIII masters.

          Aligning with CCDStack, or any astro software, will be far superior to PhotoShop.

          Cheers,
          Bob
          http://bf-astro.com


          --- In ccd-newastro@yahoogroups.com, "CurtisC" <calypte@...> wrote:
          >
          > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16 leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
          >
        • CurtisC
          TV NP101is @ f/4.32 (432 mm FL) SBIG ST-2000XM Each channel is 9 ea 20 min exposures. 6 hrs total. Some of the subs were shot in bright moonlit sky. But so
          Message 4 of 11 , Jul 31, 2011
            TV NP101is @ f/4.32 (432 mm FL)
            SBIG ST-2000XM
            Each channel is 9 ea 20 min exposures. 6 hrs total.
            Some of the subs were shot in bright moonlit sky. But so was N.A. Neb., which came out great.

            Since my message, I tried the Canistra bicolor method, which yields an interesting nebula with lots of red where Hubble palette has green. The center (mostly OIII) remains blue.

            --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@...> wrote:
            >
            > Let's start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in that area of the sky where you are? (Ha does a good job blocking light pollution, but OIII and SII are susceptible to it.)
            >
            > Ron Wodaski
            >
            >
            >
            > On Jul 30, 2011, at 11:30 PM, CurtisC wrote:
            >
            > > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16
            > > leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
            > >
            > >
            > >
            > > ------------------------------------
            > >
            > >
            > >
            > >
            >
          • CurtisC
            I like your stuff, too, Bob! Another reason to dump the gear onto Astromart and take up golf.
            Message 5 of 11 , Jul 31, 2011
              I like your stuff, too, Bob! Another reason to dump the gear onto Astromart and take up golf.

              --- In ccd-newastro@yahoogroups.com, "Bob Franke" <bfranke@...> wrote:
              >
              > Hi Curtis,
              >
              > Yes, sometimes it's not good to look at Croman's work. <g>
              >
              > The best way to do it is to align the images only once. First calibrate all of your Ha, SII and OIII subs and save into folders called "calibrated". Then load all the calibrated subs, for each filter, into CCDStack at once, align them and save into another folder called "aligned". Now you can load all the aligned subs for one filter and create your Ha, SII and OIII masters.
              >
              > Aligning with CCDStack, or any astro software, will be far superior to PhotoShop.
              >
              > Cheers,
              > Bob
              > http://bf-astro.com
              >
              >
              > --- In ccd-newastro@yahoogroups.com, "CurtisC" <calypte@> wrote:
              > >
              > > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16 leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
              > >
              >
            • CurtisC
              Sorry -- total of 9 hrs of data: 9 x 20 min in each NB color, unbinned. I didn t shoot any luminance or clear-filter frames.
              Message 6 of 11 , Jul 31, 2011
                Sorry -- total of 9 hrs of data: 9 x 20 min in each NB color, unbinned. I didn't shoot any luminance or clear-filter frames.

                --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@...> wrote:
                >
                > Let's start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in that area of the sky where you are? (Ha does a good job blocking light pollution, but OIII and SII are susceptible to it.)
                >
                > Ron Wodaski
                >
                >
                >
                > On Jul 30, 2011, at 11:30 PM, CurtisC wrote:
                >
                > > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16
                > > leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
                > >
                > >
                > >
                > > ------------------------------------
                > >
                > >
                > >
                > >
                >
              • CurtisC
                Thanks, Bob. I went into CCDStack and aligned and saved the 3 ea aligned images. Didn t know I could do it.
                Message 7 of 11 , Jul 31, 2011
                  Thanks, Bob. I went into CCDStack and aligned and saved the 3 ea aligned images. Didn't know I could do it.

                  --- In ccd-newastro@yahoogroups.com, "Bob Franke" <bfranke@...> wrote:
                  >
                  > Hi Curtis,
                  >
                  > Yes, sometimes it's not good to look at Croman's work. <g>
                  >
                  > The best way to do it is to align the images only once. First calibrate all of your Ha, SII and OIII subs and save into folders called "calibrated". Then load all the calibrated subs, for each filter, into CCDStack at once, align them and save into another folder called "aligned". Now you can load all the aligned subs for one filter and create your Ha, SII and OIII masters.
                  >
                  > Aligning with CCDStack, or any astro software, will be far superior to PhotoShop.
                  >
                  > Cheers,
                  > Bob
                  > http://bf-astro.com
                  >
                  >
                  > --- In ccd-newastro@yahoogroups.com, "CurtisC" <calypte@> wrote:
                  > >
                  > > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16 leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
                  > >
                  >
                • Ron Wodaski
                  20-minute exposures is good, but they could always be longer for any narrow-band image. You do have a fast scope, so I would expect reasonable results from
                  Message 8 of 11 , Jul 31, 2011
                    20-minute exposures is good, but they could always be longer for any narrow-band image. <g> You do have a fast scope, so I would expect reasonable results from those exposures.

                    Imaging with the moon up is always fraught with risk. Depending on how the off-axis illumination from the moon plays out - perversely, it can be worse at a position that is further away, it all depends on the light path inside the scope - you could definitely have gotten bright spots in some of your images that do not flat out. The moon reflects all of the colors of the sun, which is rich in most of the emission bands, so reflections off the moon _might_ be a hazard in variable ways. From the information you've provided, I would expect that the moon is possibly the source of the unwanted color in your final image. I suspect that your images are not really flat because of either the off-axis light, or sky gradients.

                    Ron Wodaski



                    On Jul 31, 2011, at 2:01 AM, CurtisC wrote:

                    > Sorry -- total of 9 hrs of data: 9 x 20 min in each NB color, unbinned. I didn't shoot any luminance or clear-filter frames.
                    >
                    > --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@...> wrote:
                    >>
                    >> Let's start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in that area of the sky where you are? (Ha does a good job blocking light pollution, but OIII and SII are susceptible to it.)
                    >>
                    >> Ron Wodaski
                    >>
                    >>
                    >>
                    >> On Jul 30, 2011, at 11:30 PM, CurtisC wrote:
                    >>
                    >>> I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with
                    > M16
                    >>> leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
                    >>>
                    >>>
                    >>>
                    >>> ------------------------------------
                    >>>
                    >>>
                    >>>
                    >>>
                    >>
                    >
                    >
                    >
                    >
                    > ------------------------------------
                    >
                    >
                    >
                    >
                  • Bob Franke
                    Hi Curtis, First, watch out for golf. I found golf very difficult and frustrating... imaging and bowling are easier. You have an excellent scope, all you
                    Message 9 of 11 , Jul 31, 2011
                      Hi Curtis,

                      First, watch out for golf. I found golf very difficult and frustrating... imaging and bowling are easier. You have an excellent scope, all you need is more processing experience.

                      For some great info, check out Neil Fleming's presentations at
                      http://www.flemingastrophotography.com/tipstricks.html .

                      One of Neil's most important points is to first process each channel separately, to look its best. Then do the color combine and don't use a luminance layer. This should give a result that best shows off the data from all three filters.

                      If you want to mess with the histograms, I suggest making adjustments so that left and right toes, for the three channels, are aligned. Don't try to align the hills and valleys in between. If you manage to precisely align the toes and everything in between you will have a black and white image.

                      I'm guessing that the right toe should be in the area of the histogram's center. You probably don't want to worry much about the thin line of data extending to the right of the right toe. This is mostly related to the bright stars.

                      I like to save this three-channel balanced image as my first result for web display. Then it's time to get creative with PhotoShop's Selective Color tool. Select each color and start adjusting all the sliders. After awhile, you will start to learn the result of many combinations. My tutorial shows how to go directly to the popular gold and turquoise motif.
                      http://bf-astro.com/hubbleP.htm

                      Here an interesting PhotoShop process to try.
                      First process each channel separately and then do the RGB combine. Then put a copy on a new layer and set the blend mode to color. Now we have a color layer and the background is used for luminance.

                      On the color layer, use your favorite tool to select the stars. Expand the selection a bit and then invert it. Now we have the whole image selected without the stars.

                      Next, apply Rogelio's WhiteCal PhotoShop plug-in. This will align the histograms for the three channels. This often moves the color balance towards the popular gold and turquoise motif. Here's Rogelio's WhiteCal web page.
                      http://blog.deepskycolors.com/tools.html

                      After creating some great results, here's a trick that Russ Croman sometimes uses. Paste an LRGB or RGB version as a new layer and set the opacity to about 20 to 50%. Now cycle through all the blend mode options. Something may pop up that you really like.

                      Well, that was a bit wordy... hope it helps,
                      Bob
                      http://bf-astro.com


                      --- In ccd-newastro@yahoogroups.com, "CurtisC" <calypte@...> wrote:
                      >
                      > I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with M16 leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
                      >
                    • CurtisC
                      20 min subs was a compromise choice, but they worked well with the N.A. Neb. I think the polar alignment of the mount as currently set up will support 30 min
                      Message 10 of 11 , Jul 31, 2011
                        20 min subs was a compromise choice, but they worked well with the N.A. Neb. I think the polar alignment of the mount as currently set up will support 30 min at least. It's getting too late to do much additional with M16 this year, so I'll just have to profit from the experience. I may try it with a longer FL scope next year. My main question, which was about saving aligned but uncombined frames in CCDSoft, has been answered in the affirmative.

                        --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@...> wrote:
                        >
                        > 20-minute exposures is good, but they could always be longer for any narrow-band image. <g> You do have a fast scope, so I would expect reasonable results from those exposures.
                        >
                        > Imaging with the moon up is always fraught with risk. Depending on how the off-axis illumination from the moon plays out - perversely, it can be worse at a position that is further away, it all depends on the light path inside the scope - you could definitely have gotten bright spots in some of your images that do not flat out. The moon reflects all of the colors of the sun, which is rich in most of the emission bands, so reflections off the moon _might_ be a hazard in variable ways. From the information you've provided, I would expect that the moon is possibly the source of the unwanted color in your final image. I suspect that your images are not really flat because of either the off-axis light, or sky gradients.
                        >
                        > Ron Wodaski
                        >
                        >
                        >
                        > On Jul 31, 2011, at 2:01 AM, CurtisC wrote:
                        >
                        > > Sorry -- total of 9 hrs of data: 9 x 20 min in each NB color, unbinned. I didn't shoot any luminance or clear-filter frames.
                        > >
                        > > --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@> wrote:
                        > >>
                        > >> Let's start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in that area of the sky where you are? (Ha does a good job blocking light pollution, but OIII and SII are susceptible to it.)
                        > >>
                        > >> Ron Wodaski
                        > >>
                        > >>
                        > >>
                        > >> On Jul 30, 2011, at 11:30 PM, CurtisC wrote:
                        > >>
                        > >>> I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with
                        > > M16
                        > >>> leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
                        > >>>
                        > >>>
                        > >>>
                        > >>> ------------------------------------
                        > >>>
                        > >>>
                        > >>>
                        > >>>
                        > >>
                        > >
                        > >
                        > >
                        > >
                        > > ------------------------------------
                        > >
                        > >
                        > >
                        > >
                        >
                      • CurtisC
                        Sorry, I left off part of my post. Thank you for your help and advice :)
                        Message 11 of 11 , Jul 31, 2011
                          Sorry, I left off part of my post. Thank you for your help and advice :)

                          --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@...> wrote:
                          >
                          > 20-minute exposures is good, but they could always be longer for any narrow-band image. <g> You do have a fast scope, so I would expect reasonable results from those exposures.
                          >
                          > Imaging with the moon up is always fraught with risk. Depending on how the off-axis illumination from the moon plays out - perversely, it can be worse at a position that is further away, it all depends on the light path inside the scope - you could definitely have gotten bright spots in some of your images that do not flat out. The moon reflects all of the colors of the sun, which is rich in most of the emission bands, so reflections off the moon _might_ be a hazard in variable ways. From the information you've provided, I would expect that the moon is possibly the source of the unwanted color in your final image. I suspect that your images are not really flat because of either the off-axis light, or sky gradients.
                          >
                          > Ron Wodaski
                          >
                          >
                          >
                          > On Jul 31, 2011, at 2:01 AM, CurtisC wrote:
                          >
                          > > Sorry -- total of 9 hrs of data: 9 x 20 min in each NB color, unbinned. I didn't shoot any luminance or clear-filter frames.
                          > >
                          > > --- In ccd-newastro@yahoogroups.com, Ron Wodaski <yahoo@> wrote:
                          > >>
                          > >> Let's start with some basics. What is the focal ratio of that scope? What camera are you using? How long are your exposures? Is there any light pollution in that area of the sky where you are? (Ha does a good job blocking light pollution, but OIII and SII are susceptible to it.)
                          > >>
                          > >> Ron Wodaski
                          > >>
                          > >>
                          > >>
                          > >> On Jul 30, 2011, at 11:30 PM, CurtisC wrote:
                          > >>
                          > >>> I may not even be asking the question properly, or I may not correctly understand what I've been reading. I'm getting into narrowband imaging (Ha, OIII, SII). The North America Nebula practically fell together as a Hubble palette image, and I was able to achieve a spectacular result that got lots of "likes" and compliments. M16 has been a lot -- a lot!! -- more difficult. Apparently the fact that it's 3x farther than the N.A. and possibly 1/9 as bright is probably part of my problem. What I'm reading about narrowband says I should align the images (not just the subs within each color) before working on them in Photoshop. The question: can CCDStack save each image as though it were aligned with a base image (say, the H-alpha) without having to actually combine them? For some reason, people seem to be cool to the idea of using auto-align in PS. I wouldn't use it for the subs, but it seems to work well enough for aligning the three colors. In addition, everything I do with
                          > > M16
                          > >>> leaves me with lots of green in the outer parts of the nebula. I was just looking at a narrowband image of M16 by Russell Croman, and it was almost enough to make me want to put all of my equipment on Astromart. Of course, he did it with a 20-inch scope vs. my 4-inch, but even in the central part that he shows, I haven't been able to get close to what he has.
                          > >>>
                          > >>>
                          > >>>
                          > >>> ------------------------------------
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